Two pot experiments were performed in Old Botanical Garden, University of Agriculture, Faisalabad to explore the role of exogenous application of β-carotene as foliar spray on fennel under saline conditions. Two fennel varieties Dulce and Indigenous were tested against salinity, i.e. 0 mM NaCl (Control) and 120 mM NaCl. Three levels of β-carotene 0 (water spray), 0.25 and 0.5 mM were applied through foliar spray. Salinity was maintained after 40 days of sowing. β-carotene treatment as foliar spray was applied after three weeks of salinity development. Salinity prominently reduced the growth and yield of fennel plant by reducing shoot fresh and dry weights, shoot length, photosynthetic pigments (Chlorophyll a and b, total chlorophyll and carotenoids). Shoot and root Na⁺, Ca²⁺ and K⁺ along with leaf MDA and H₂O₂ prominently increased. Imposition of salinity increased the level of antioxidants (catalase, peroxidase, superoxide dismutase, flavonoids and total phenolics), osmoprotectants (proline) and total soluble proteins. Exogenous spray of β-carotene improved the  fresh and dry weight of shoot,  length of shoot, antioxidants, osmoprotectants and also decreasing ROS production and shoot and root Na⁺. Foliar application of β-carotene  alleviate the destructive effects of salt stress in fennel plant. Of various β-carotene levels, 0.5 mM concentration showed more improvement in growth and yield of fennel plant as compared to others. Fennel variety Dulce proved to be more salt tolerant and showed better growth in all parameters as compared to Indigenous variety.

Index-terms: Fennel, β-carotene, salt stress, antioxidants, osmoprotectants, photosynthetic pigments